1. Field of the Invention
The present invention relates to an image processing apparatus and method associated with color matching processing for digital color image data and transfer of a profile used for color matching processing.
2. Related Background Art
In recent years, along with the development of digital coding techniques, methods of compressing/coding image data and transmitting the image data as digital data have been established to enable transmission of high-quality video data obtained by, e.g., a video camera. In a multimedia system having a host computer as a core equipment, extensive studies of a color matching system (to be referred to as a CMS hereinafter) for matching the color appearances between input image data and output devices have been made. In ColorSync of Apple computer Inc., which is one of the frameworks of representative CMSs, the device dependent color space of an input device is converted into an independent color space, thereby realizing common CMS processing. For this conversion processing, data (profile) representing the device dependent color space conversion characteristic is prepared in the host computer in units of devices, so that the color space is converted in accordance with the conversion characteristic which is automatically or manually selected in conversion processing.
FIG. 21 is a block diagram showing the relationship between an image transmission technique and a CMS in the prior art. On the transmission side, digital image data is input from a terminal 1601. An error correction coding circuit 1602 adds parity data for correcting data errors on the transmission line to the digital image data. The digital image data to be sent to the transmission line is subjected to packeting and modulation by a transmission line coding circuit 1603, and transmitted from a terminal 1604. In a host computer 1605 on the reception side, a transmission line decoding circuit 1607 decodes the transmission data supplied from a terminal 1606 and extracts a data block from the transmission packet. The data is subjected to transmission line error correction processing by an error correction circuit 1608 and output from a terminal 1609 as digital image data. Color space characteristic data for CMS processing is prepared in advance as a permanent data file 1610 in the host computer. Therefore, the color space characteristic data does not dynamically reflect the characteristic of the transmitted digital image data.
In the conventional system, when, e.g., a flatbed scanner is directly connected to the host computer, and the characteristic of the input device itself does not change, the effect of CMS processing can be expected by using the conversion characteristic data stored in the host computer. However, assume that a signal whose characteristic in the actual read process cannot be specified, like compressed and coded digital image data and, particularly video camera image data largely depending on the adjustment state in a pickup operation, is digitally coded, transmitted, and subjected to CMS processing. In this case, only with the conversion characteristic data prepared in the host computer, no sufficient effect can be expected. In addition, erroneous conversion is undesirably performed in accordance with an unsuitable characteristic.